Teammates lied to the enemy team, claiming I verbally abused them. Thoughts?

Here's a rundown of what happened:

During champ select, our teammates and I chose our champions. Our team comp wasn't out of the ordinary, consisting of a top lane bruiser, mid assassin, tank jungler, and regular adc/support bot. Halfway through champ select, one of my teammates says "GG". At first, I don't think much of it, but then during the match, after losing several kills, two of our teammates (I was queued with a friend) AFK'ed in the fountain. Up until this point, I hadn't said a single word to anyone, but at this point, it was obvious that our teammates intended to sit at base; in all chat, I requested the enemy team to report those two teammates for going AFK, which prompted them to respond by saying that I should have been reported for verbal abuse, claiming that I used the "N" word to disparage them. I continued to play normally, while after a few minutes, the AFK teammates came back out of fountain and began intentionally feeding kills.

Once the match was over, I received a notice warning me for verbal abuse, likely due to multiple reports from said teammates and potentially a few players on the opposing team; I once again reiterated that I never said a single (negative) word toward my teammates, but they continued to lie toward the enemy team, claiming that I had called them "fat". The warning I received is completely uncalled for on my part - I, for one, have NEVER used a racist, homophobic, or otherwise inflammatory insult toward a teammate or opponent; it comes off as very nonsensical that I received this warning, when over the past several days, I have even been honored multiple times by strangers/teammates for being a Friendly player.

Now, it's obvious that my teammates decided to troll me, but going as far as to report me for verbal abuse and convince the enemy team to do it?

I'd like to know how to deal with situations like this. If someone at Riot were to view a replay of that match, they'd KNOW that I never used the "N" word, or even said anything to my teammates to begin with. It would be nice if me receiving that warning was undone, though honestly it's not big deal. Still, thoughts?

Please let me know if this post should be elsewhere.